The present invention relates to a method of driving a pixel circuit, a pixel circuit, an electro-optical device and an electronic apparatus, and more particularly, to an optical feedback type pixel circuit having a built-in photoelectric transducer built.
Recently, a flat panel display (FPD) using an organic EL (electronic luminescence) element has been drawing attention. The organic EL element is an example of current-driven elements driven by a driving current flowing therein to emit light with a brightness corresponding to the current level. In an organic EL display, the difference in the characteristics of the organic EL element (particularly, current-brightness characteristic) adversely influences the uniformity of display. Further, it has been known that the organic EL element has a large degree of temporal degradation as compared to an element made of other materials such as liquid crystal. For this reason, in the organic EL display, the degree of degradation between the elements is varied according to the displayed images, so that burn-in is easily generated in the screen.
In order to solve these problems, Patent Document 1 proposed an optical feedback type pixel circuit having a photoelectric transducer built therein. The pixel circuit includes a driving transistor for supplying a driving current to a light-emitting element, a capacitor for applying a gate voltage to the driving transistor, and a photoelectric transducer connected in parallel to the capacitor for receiving a photoelectric current according to the intensity of the received light. The photoelectric transducer generates a photoelectric current according to the intensity of the received light. The electric charge stored as data in a capacitor is discharged according to the photoelectric current. In a light-emitting element having a high light-emitting efficiency and high brightness, since the photoelectric current is large, the light emitting attenuates relatively fast. On the other hand, in a light-emitting element having a low light-emitting efficiency and low brightness, since the photoelectric current is small, the light emitting attenuates relatively slow. As a result, even though the characteristics of the light-emitting elements are different, since the integral value of the brightness in the overall one frame is substantially the same, the difference in characteristics of the light-emitting elements is compensated.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2003-509728